THE EFFECT OF FILLER SURFACE MODIFICATION ON THE MECHANICAL-PROPERTIES OF ALUMINUM HYDROXIDE FILLED POLYPROPYLENE

Aluminium hydroxide (Al(OH)(3))) has been treated with a range of surf ace modifiers including a dicarboxylic acid anhydride (DAA), a silane based system and a maleanised polybutadiene (MPBD). Polypropylene (PP) based composites were produced by twin screw extrusion and their mech anical properties evaluated. At filler levels below those required for effective flame retardation, the DAA treated filler gave the composit e with the best mechanical properties. At higher filler levels, i.e. a bove 50% w/w, the composites based on Al(OH)(3) coated with the strong ly coupling silane afforded the best properties. The latter treatment proved to be most effective when the polymer matrix was an impact modi fied PP. This was due to encapsulation of the filler particles by the elastomeric impact modifier phase of the matrix. MPBD treated Al(OH)(3 ) gave a composite with improved properties relative to the DAA treate d Al(OH)(3). However, the absence of any encapsulation effect resulted in these composites having inferior properties to those based on the silane treated AL(OH)(3).